1. Field of the Invention
This invention relates to a method and an apparatus for forming graphs on the basis of numerical data and, in particular, to a method and an apparatus for forming graphs with partial omissions.
2. Description of the Related Art
By using an apparatus of this type, which is capable of forming and displaying graphs, it has been possible to form various kinds of graphs on the basis of numerical data like table-calculation data, thereby easily visualizing numerical fluctuations to facilitate achievement analysis, etc.
With such an apparatus, the scale of the relevant graph axis is determined automatically when the numerical data to be presented in the form of a graph is designated by the operator. This axis scale is usually displayed in a continuous form with the scale division set by taking into consideration the range from "0" to the maximum value of the numerical data, so that all the designated numerical data is displayed.
In the case of data which, when displayed in the form of a graph, exhibit such small differences therebetween as to be rather difficult to read, the following conventional measure may be taken: the section between the maximum and minimum values of these items of data is enlarged, and the section below the minimum value of the data is omitted. This makes it possible to present the differences between these items of data in a focused, enlarged state while preventing the graph as a whole from becoming excessively large.
However, such conventional methods and apparatuses for forming graphs have a problem in that they allow only the section below the minimum value of the numerical data to be omitted. Therefore, the above omitting method has not been applicable to numerical data of a type in which the values thereof are dispersed in such a way as to be grouped around maximum and minimum values.
Another problem with conventional methods and apparatuses for forming graphs is that the display range of a graph representing any designated numerical data is determined from the maximum and minimum values of the numerical data. Thus, in the case of numerical data dispersed over such a wide range that the ratio of the difference between the maximum and minimum values to the maximum value is large, it has been impossible to form a graph with satisfactory display efficiency.
Further, with conventional methods and apparatuses for forming graphs, it has been impossible for the operator to arbitrarily designate the graph range to be omitted so that the portion on which the operator wishes to concentrate can be presented in a focused state.
Still further, when data represented, for example, as a connected-line graph, is displayed with a partial omission, no technique has been available in conventional methods and apparatuses for forming graphs which would make it possible to display a line connecting the data displayed on one side of the omitted section to the data on the other side thereof or a line connecting the data which has been omitted in the display to the data on either side of the omitted section.